Java Part 2: Basic Data Types and Variables in Java

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DATA TYPES AND VARIABLES IN JAVA

Java is a popular programming language that is known for its strong-typing. In Java, every variable and expression has a specific data type that defines the kind of values it can hold. Java supports several built-in data types that can be used to define variables. In this article, we’ll discuss the basic data types and variables in Java.

Primitive Data Types:

Java has eight primitive data types, which are divided into four categories:

Integer Types:
- byte: 8-bit signed two’s complement integer.
- short: 16-bit signed two’s complement integer.
- int: 32-bit signed two’s complement integer.
- long: 64-bit signed two’s complement integer.
Floating-Point Types:
- float: 32-bit IEEE 754 floating-point number.
- double: 64-bit IEEE 754 floating-point number.
Character Type:
- char: 16-bit Unicode character.
Boolean Type:
- boolean: represents one of two values: true or false.

Variables:

Variables are used to store values in Java, and are defined with a specific data type. To define a variable, you need to specify the data type, followed by the variable name. Here’s an example:

int age = 25;

In the above example, we have defined a variable called “age” of type “int”, and assigned it a value of 25.

You can also declare multiple variables of the same type on the same line, like this:

int age = 25, height = 175;

It’s important to note that when you define a variable, you are only reserving memory space for it. To assign a value to the variable, you need to use the assignment operator (=).

Example Code

Here’s an example code that demonstrates the use of basic data types and variables in Java:

public class Main {
  public static void main(String[] args) {
    // Integer data type
    int a = 42;
    System.out.println("Value of a: " + a);
    System.out.println("Data type of a: " + Integer.TYPE);

    // Float data type
    float b = 3.14f;
    System.out.println("Value of b: " + b);
    System.out.println("Data type of b: " + Float.TYPE);

    // Double data type
    double c = 2.71828;
    System.out.println("Value of c: " + c);
    System.out.println("Data type of c: " + Double.TYPE);

    // Boolean data type
    boolean d = true;
    System.out.println("Value of d: " + d);
    System.out.println("Data type of d: " + Boolean.TYPE);

    // Character data type
    char e = 'A';
    System.out.println("Value of e: " + e);
    System.out.println("Data type of e: " + Character.TYPE);

    // Array data type
    int[] f = {1, 2, 3, 4, 5};
    System.out.print("Value of f: [");
    for (int i = 0; i < f.length; i++) {
      System.out.print(f[i]);
      if (i != f.length - 1) {
        System.out.print(", ");
      }
    }
    System.out.println("]");
    System.out.println("Data type of f: " + f.getClass().getComponentType());

    // String data type
    String g = "Hello, World!";
    System.out.println("Value of g: " + g);
    System.out.println("Data type of g: " + g.getClass().getSimpleName());

    // Object data type
    Person h = new Person("John", 30);
    System.out.println("Value of h: " + h);
    System.out.println("Data type of h: " + h.getClass().getSimpleName());
  }
}

class Person {
  private String name;
  private int age;

  public Person(String name, int age) {
    this.name = name;
    this.age = age;
  }

  public String toString() {
    return "Person [name=" + name + ", age=" + age + "]";
  }
}

Output:

Value of a: 42
Data type of a: int
Value of b: 3.14
Data type of b: float
Value of c: 2.71828
Data type of c: double
Value of d: true
Data type of d: boolean
Value of e: A
Data type of e: char
Value of f: [1, 2, 3, 4, 5]
Data type of f: int
Value of g: Hello, World!
Data type of g: String
Value of h: Person [name=John, age

In the above code, we have declared and initialized variables of different data types, and then printed out their values and types using the System.out.println() method.

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